1. Field of the Invention
The present invention is concerned with combination hanger and expansion plate structure for use in supporting and spacing refractory bricks in furnace constructions. More particularly, it is concerned with specialized plates of this type which include brick-engaging projection surfaces configured such that the projection surfaces adjacent the hot faces of the bricks will yield when subjected to high temperature conditions and consequent lateral expansion of the furnace bricks, while the projection surfaces adjacent the opposite or cold faces of the bricks will remain substantially intact.
2. Description of the Prior Art
Metal encased refractory bricks have long been employed to construct electric furnace roofs. Generally speaking, these encased bricks are arranged in a predetermined pattern and are suspended by means of conventional hangers or the like. For the most part, bricks of this type are constructed as a unit, i.e., the refractory brick is encased within a surrounding metallic sleeve at the factory.
It has also long been recognized that refractory bricks, when subjected to high furnace temperatures, expand in a variable fashion. That is to say, the lateral expansion of the bricks is greatest adjacent the so-called "hot faces" thereof, or the faces which define the internal surface of the roof. On the other hand, the heat-induced expansion adjacent the cold or exterior faces of the bricks is much less. As can be appreciated, a unitary, permanently attached casing or sleeve around a refractory brick cannot really accommodate variable expansion. In fact, it is known that refractory brick life is considerably lessened because of this shortcoming with conventional encased bricks.
Prior refractory brick constructions of the type discussed above are illustrated in the following patents: U.S. Pat. Nos. 3,282,231, 3,174,444, 3,280,772, 2,125,192, 2,266,785, 2,281,200, 2,885,976, 2,960,048, 2,991,736, 3,083,453, 3,181,486, 3,416,780, 3,252,436, 3,073,067, 3,205,842, 3,213,533, 3,566,571, 3,287,872 and French Pat. No. 1,251,356.